A. Technical Field
The present invention relates to a method of insulating a cargo container and an insulated or refrigerated cargo container. In one embodiment, the cargo container is a railroad boxcar.
B. Related Art
Currently, many shippers utilize insulated or refrigerated large cargo containers (such as boxcars) to transport items that require the maintenance of specified temperatures during transit. Because these containers are required to maintain certain temperatures, the thermal efficiency of these containers is an important feature. Thermal efficiency is characterized by the thermal conductivity of a particular component or its inverse, its resistance to heat transfer commonly referred to as an R value.
In the past, large cargo containers were typically constructed of a combination of wood and metal members. Because members of this type typically possessed a low R-value, insulation, such as foam insulation, was often installed in these cargo containers to increase their thermal efficiency. Even with the use of insulation, however, the thermal efficiency of cargo containers of this type has not been as high as desired by users of these cargo containers. Therefore, there is a need for methods of constructing cargo containers with improved thermal efficiency.
One such existing method has involved placing additional insulating materials on the interior of the container. One drawback of this method is that placing additional insulating materials on the interior of the container reduces the interior dimensions of the cargo container. In turn, reducing the interior dimensions of the cargo container reduces the amount of space available for cargo. In addition, insulating materials located on the interior of a cargo container can also be subject to damage from the placement of cargo in the containers. This also reduces the thermal efficiency of the cargo container. Therefore, there is a need for methods of constructing cargo containers with improved thermal efficiency without substantially reducing the interior dimensions of the car and making the insulating panels less susceptible to loading damage.
The present invention provides a method of constructing cargo containers with improved thermal efficiency without reducing the interior dimensions of the container.